The present invention generally relates to a sensing arrangement for measuring the rotational speed of a rotatable shaft and more particularly to such an arrangement for a shaft having at least one crank.
From German Published Unexamined Patent Application No. (DE-OS) 24 24 991, an arrangement is shown which senses the crankshaft rotational speed of an internal-combustion engine by means of a scanning disk which rotates adjacent a stationary sensor. In this case, a scanning disk is fitted outside of the crankcase onto the crankshaft which extends out of the engine toward the front.
In the above-noted arrangement, it is only possible to determine the crankshaft rotational speed by fitting the disk onto the front or rear end of the crankshaft. Because of the crankshaft throw, it is not possible to mount the disk at any arbitrary point of the crankshaft.
Thus, it is an object of the present invention to provide a sensing arrangement for measuring crankshaft rotational speed at any arbitrary point of a crankshaft.
It is a further object of the present invention to provide such a sensing arrangement which can be easily mounted and removed from the crankshaft, even after installation in an engine or the like.
It is a still further object of the present invention to provide a sensing arrangement for measuring the rotational speed of an internal combustion engine.
According to certain advantageous embodiments of the present invention, these and other objects are achieved by utilizing a scanning ring which form fittingly engages a crankshaft web after being radially bent open over a cylindrical part of a crankshaft.
In order to facilitate mounting of this type of a scanning ring easily at any arbitrary point, in one embodiment of the present invention, the scanning ring is provided with two legs which form an L-shaped cross-section and teeth at one of the legs, a recess being provided at a point approximately opposite a radially extending gap for permitting a bending opening of the ring during installation on a shaft.
Advantages achieved by preferred embodiments of the present invention include, in particular, that the scanning ring can be fastened at an arbitrary web of the crankshaft even after the crankshaft has been mounted into the crankcase, and that this mounting operation may take place in a simple manner without any expensive technical devices. In addition, the scanning ring can be manufactured at low cost as a stamped metal part.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.